Addressing a crowd at the fourth annual South Carolina Tea Party Coalition Convention, Rick Santorum continued to sound a populist tone and hammer Mitt Romney for managing to muster only 19 percent of support among middle class voters in 2012.

"Lower or middle income folks who are struggling. And guess what, our candidate only got [about] 19 percent of that vote.

"We better have a party and a movement that addresses and cares about the people who are losing hope and feeling like America doesn’t work for them anymore,” said Santorum, according to Politico.

Santorum's attack underscores what could be a potential problem for Romney — an inability to convey a sense that he "cares" about the concerns of average Americans.

"One of the biggest reasons Romney lost is because Americans didn't view him as relatable — and much of that problem was fundamental to his biography. Democrats had a wealth of material to use in portraying his successful business background as something far more sinister.

Romney and his staff would also need to recognize what they did not in 2012 — that he lost the middle class vote to Obama.

"On Nov. 6, Romney carried the majority of every economic group except those with less than $50,000 a year in household income. That means he carried the majority of middle-class voters," wrote Romney adviser Stuart Stevens in The Washington Post shortly after the election.

While income inequality and middle class concerns have emerged as central themes among candidates from both parties, Santorum began focusing on those issues last April with the publication of "Blue Collar Conservatives," a book in which he counseled the Republican Party to speak to the concerns of middle class voters.

"I wrote this book for people to understand that the answer to the problems they’re struggling with is not, as they know, the left and progressive politics, driving up the cost of labor and making it more expensive to hire people.

"The answer is something that has not been put forth by any politician in recent times, which is the pro-growth, pro-worker agenda," Santorum told U.S. News & World Report last spring.

It is a theme that he even evoked in a statement released Tuesday announcing that Roy Jones and Rob Bickhart were joining Executive Director Nadine Maenza on the finance team of Patriot Voices, his political action committee.

Santorum said they "will play a crucial role in ensuring we have the resources necessary to be a leader in the coming national debate, particularly as we tackle challenges confronting blue-collar families across this country."

Focusing on "blue-collar" issues is one way in which Santorum plans to make his possible campaign for president in 2016 different than the race he ran in 2012.

“I don’t think I’ve met a 'suit' yet. It’s very much heart of America, average Americans who have found a place where they see someone who will stand up and fight for them.

"If the Republican Party has a future — and I sometimes question if it does — it’s in middle America. It’s not in corporate America," the former Pennsylvania senator told The Washington Post in a December interview.

Rick Santorum, speaking at the tea party convention in South Carolina, continued to sound a populist tone and hammer Mitt Romney for managing to muster only 19 percent of support among middle class voters in 2012.